Method and apparatus for allocating resources in wireless communication system

ABSTRACT

A multiple distributed system is disclosed. An uplink control resource allocation method for a user equipment to transmit an Acknowledgement/Negative ACK (ACK/NACK) signal includes receiving one or more Enhanced-Physical Downlink Control Channels (E-PDCCHs), receiving one or more Physical Downlink Shared Channels (PDSCHs) corresponding to the one or more E-PDCCHs, and transmitting ACK/NACK signals for reception of the one or more PDSCHs through a Physical Uplink Control Channel (PUCCH), wherein Control Channel Element (CCE) indexes of the PUCCH transmitting the ACK/NACK signals are determined in consideration of first CCE indexes of the one or more E-PDCCHs and the number of CCEs of a PUCCH determined by a higher layer.

TECHNICAL FIELD

The present invention relates to a wireless communication system and,more particularly, to a method and apparatus for allocating frequencyresources of new control channels presenting in data regions of nodes ina distributed multi-node system.

BACKGROUND ART

Recently, attention is being paid to a Multiple-Input Multiple--Output(MIMO) system to maximize the performance and communication capacity ofa wireless communication system. MIMO technology refers to a schemecapable of improving data transmission/reception efficiency usingmultiple transmit antennas and multiple receive antennas, instead ofusing a single transmit antenna and a single receive antenna. The MIMOsystem is also called a antenna system. MIMO technology applies atechnique of completing a whole message by gathering data fragmentsreceived via several antennas without depending on a single antenna pathin order to form one whole message. Consequently, MIMO technology canimprove data transmission rate in a specific range or increase a systemrange at specific data transmission rate.

MIMO technology includes transmit diversity, spatial multiplexing, andbeamforming. Transmit diversity is technique for increasing transmissionreliability by transmitting the same data through multiple transmitantennas. Spatial multiplexing is a technique capable of transmittingdata at high rate without increasing system bandwidth by simultaneouslytransmitting different data through multiple transmit antennas.Beamforming is used to increase a Signal to Interference plus NoiseRatio (SNR) of a signal by adding a weight to multiple antennasaccording to a channel state. In this case, the weight can be expressedby a weight vector or a weight matrix, which is respectively referred toas a precoding vector or a precoding matrix.

Spatial multiplexing is divided into spatial multiplexing for a singleuser and spatial multiplexing for multiple users. Spatial multiplexingfor a single user is called Single User MIMO (SU-MIMO) and spatialmultiplexing for multiple users is called Spatial Division MultipleAccess (SDMA) or Multi User MIMO (MU-MIMO).

The capacity of a MIMO channel increases in proportion to the number ofantennas. The MIMO channel may be divided into independent channels.Assuming that the number of transmit antennas is Nt and the number ofreceive antennas is Nr, the number of independent channels, Ni, isNi=min{Nt, Nr}. Each of the independent channels may be said to be aspatial layer. A rank is the number of non-zero eigenvalues of a MIMOchannel matrix and may be defined as the number of spatial streams thatcan be multiplexed.

In the MIMO system, each transmit antenna has an independent datachannel. The transmit antenna may mean a virtual antenna or a physicalantenna. A receiver estimates a channel for each transmit antenna toreceive data transmitted from each transmit antenna. Channel estimationrefers to a process of restoring a received signal by compensating fordistortion of the signal caused by fading. Fading refers to a phenomenonin which signal strength abruptly varies due to multi-path time delay ina wireless communication system environment. For channel estimation, areference signal that is known to both a transmitter and a receiver isneeded. The reference signal may be referred simply to as an RS or maybe referred to as a pilot according to applied standard.

A downlink reference signal is a pilot signal for coherent demodulationof a Physical Downlink Shared Channel (PDSCH), a Physical Control FormatIndicator Channel (PCFICH), a Physical Hybrid indicator Channel (PHICH,a Physical Downlink Control Channel (PDCCH), etc. The downlink referencesignal includes a Common Reference Signal (CRS) shared by all UserEquipments (UEs) in a cell and a Dedicated Reference Signal (DRS) for aspecific UE. The CRS may be called a cell-specific reference signal andthe DRS may be called UE-specific reference signal.

As compared to a legacy communication system supporting a transmitantenna, (e.g. a system according to LTE releases 8 or 9), a systemhaving an extended antenna configuration, (e.g. a system supporting 8transmit antennas according to LTE-A), needs to transmit a referencesignal for obtaining Channel State Information (CSI), i.e. a CSI-RS, ina receiver.

DISCLOSURE Technical Problem

An object of the present invention is to provide a method and apparatusfor efficiently allocating resources for a physical channel in awireless communication system. Another object of the present inventionis to provide a channel format and signal processing for efficientlytransmitting control information, and an apparatus therefor. A furtherobject of the present invention is to provide a method and apparatus forefficiently allocating resources for transmitting control information.

It will be appreciated by persons skilled in the art that that thetechnical objects that can be achieved through the present invention arenot limited to what has been particularly described hereinabove andother technical objects of the present invention will be more clearlyunderstood from the following detailed description.

Technical Solution

The object of the present invention can be achieved by providing anuplink control resource allocation method for a user equipment totransmit an Acknowledgement/Negative ACK (ACK/NACK) signal in a wirelesscommunication system, including receiving one or more Enhanced-PhysicalDownlink Control Channels (E-PDCCHs), receiving one or more Physical.Downlink Shared Channels (PDSCHs) corresponding to the one or moreE-PDCCHs, and transmitting ACK NACK signals for reception of one or morePDSCHs through a Physical Uplink Control Channel (PUCCH), wherein.Control Channel Element (CCE) indexes of the PUCCH transmitting the ACK/HACK signals are determined in consideration of first CCE indexes ofthe one more E-PDCCHs and the number of CCE's of a PUCCH determined by ahigher layer.

In another aspect of the present invention, provided herein is a methodfor a base station to receive an Acknowledgement/Negative ACK (ACK/NACK)signal according to uplink control resource allocation in a wirelesscommunication system, including transmitting one or moreEnhanced--Physical Downlink Control Channels (E-PDCCHs), transmittingone or more Physical Downlink Shared Channels (PDSCHs) corresponding tothe one or more E-PDCCHs, and receiving ACK/NACK signals fortransmission of the one or more PDSCHs through a Physical Uplink ControlChannel (PUCCH), wherein Control Channel Element (CCE) indexes of thePUCCH receiving the ACK/NACK signals are determined in consideration offirst CCE indexes of the one or more E-PDCCHs and the number of CCEs ofa PUCCH determined by a higher layer.

In a further aspect of the present invention, provided herein is a userequipment for allocating resources for uplink control to transmit.Acknowledgement/Negative ACK (ACK/NACK) signal in a wirelesscommunication system, including a Radio Frequency (RF) unit, and aprocessor, wherein the processor controls the RF unit to receive one ormore Enhanced-Physical Downlink Control Channels (E-PDCCHs), receive oneor more Physical Downlink. Shared Channels (PDSCHs) corresponding to theone or more E-PDCCHs, and transmit ACK/NACK signals for reception of theone or more PDSCHs through a Physical. Uplink Control Channel (PUCCH),and wherein Control Channel Element (CCE) indexes of the PUCCHtransmitting the ACK/NACK signals are determined in consideration offirst CCE indexes of the one or more E-PDCCHs and the number of CCEs ofa PUCCH determined by a higher layer.

In still another aspect of the present invention, provided herein is abase station for receiving an Acknowledgement/Negative ACK (ACK/NACK)signal according to uplink control resource allocation in a wirelesscommunication system, including a Radio Frequency (RF) unit, and aprocessor, wherein the processor controls the RF unit to transmit one ormore Enhanced-Physical Downlink Control Channels (E-PDCCHs), transmitone or more Physical Downlink Shared Channels (PDSCHs) corresponding tothe one or more E-PDCCHs, and receive ACK/NACK signals for transmissionof the one or more PDSCHs through a Physical Uplink Control Channel(PUCCH), and wherein Control Channel Element (CCE) indexes of the PUCCHreceiving the ACK/NACK signals are determined in consideration of firstCCE indexes of the one or more E-PDCCHs and the number of CCEs of aPUCCH determined by a higher layer.

The CCE indexes of the PUCCH transmitting the ACK/NACK signals may bedetermined by the sum of the first CCE indexes of the one or moreE-PDCCHs and the number of CCEs of the PUCCH determined by the higherlayer.

First CCE indexes of the one or more E-PDCCHs in an interleaving regionmay be determined by further considering a total number of CCEs of aPDCCH.

The first CCE indexes of the one or more E-PDCCHs in a non-interleavingregion may be minimum resource block indexes of the one or more E-PDCCHsand may be determined by further considering a total number of CCEs ofthe PDCCH.

If the user equipment monitors a region of the PDCCH, the user equipmentmay calculate a total number of CCEs of the PDCCH and, if the userequipment does not monitor the region of the PDCCH, the user equipmentmay receive the total number of CCEs of the PDCCH from a base station.

If an interleaving region and a non-interleaving region share a resourceregion of the PUCCH, a resource index of the PUCCH may be determined byfurther considering the total number of CCEs of the PUCCH in theinterleaving region.

The first CCE indexes of the E-PDCCHs may be determined based on the CCEindexes of the PUCCH transmitting the ACK/NACK signals by configuringDemodulation Reference Signal (DMRS) antenna port.

The CCE indexes of the PUCCH transmitting the ACK/NACK signals may besemi-statically configured through additional signaling and may beconfigured by dividing regions according to each. E-PDCCH set.

ADVANTAGEOUS EFFECTS

According to embodiments of the present invention, resources for aphysical channel can be efficiently allocated in a wirelesscommunication system, desirably, in a distributed multi-node system.

It will be appreciated by persons skilled in the art that that theeffects that can be achieved through the present invention are notlimited to what has been particularly described hereinabove and otheradvantages of the present invention will be more clearly understood fromthe following detailed description.

DESCRIPTION OF DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention, illustrate embodiments of the inventionand together with the description serve to explain the principle of theinvention.

In the drawings:

FIG. 1 illustrates the structure of a DAS to which the present inventionis applied;

FIG. 2 illustrates a control region in which a PDCCH can he transmittedin a 3GPP LTE/LTE-A system;

FIG. 3 illustrates the structure of a UL subframe used in a 3GPP system;

FIG. 4 illustrates an E-PDCCH and a PDSCH scheduled by the E-PDCCH;

FIG. 5 illustrates the structure of an R-PDCCH transmitted to a relaynode;

FIG. 6 illustrates allocation of an E-PDCCH according to prior art 1);

FIG. 7 illustrates allocation of an E-PDCCH according to prior art 2);

FIG. 8 illustrates cross-interleaving of an E-PDCCH;

FIG. 9 illustrates exemplary allocation of an E-PDCCH to a resourceconfiguration region for cross interleaving or non-cross interleavingaccording to an exemplary embodiment of the present invention;

FIG. 10 conceptually illustrates a first CCE index^(n) ^(CCE) ;

FIG. 11 illustrates physical mapping of a PUCCH format to a PUCCHresource block or region;

FIG. 12 illustrates the relationship between a PUCCH resource index anda physical RB index m;

FIG. 13 illustrates search space concatenation based on N_(CCF)according to the present invention;

FIG. 14 illustrates separate configuration of a PUCCH ACK/NACK resourcefor an E-PDCCH according to the present invention; and

FIG. 15 illustrates a BS and a UE which are applicable to an exemplaryembodiment of the present invention.

BEST MODE

Reference will now be made in detail to the exemplary embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings. The detailed description, which will be given below withreference to the accompanying drawings, is intended to explain exemplaryembodiments of the present invention, rather than to show the onlyembodiments that can be implemented according to the invention. Thefollowing detailed description includes specific details in order toprovide a thorough understanding of the present invention. However, itwill be apparent to those skilled in the art that the present inventionmay be practiced without such specific details. For example, althoughthe following detailed description is given under the assumption of a3GPP LTE system or an IEEE 802.16m system it is applicable to othermobile communication systems except for matters that are specific to the3GPP LTE system or IEEE 802.16m system.

In some instances, known structures and devices are omitted or are shownin block diagram form, focusing on important features of the structuresand devices, so as not to obscure the concept of the present invention.The same reference numbers will be used throughout this specification torefer to the same parts.

A wireless communication system to which the present invention isapplicable includes at least one Base Station (BS). Each BS provides acommunication service to a User Equipment (UE) located in a specificgeographic area (generally, referred to as a cell). The UE may be fixedor mobile and includes various devices that transmit and receive userdata an control information through communication with the BS. The UEmay be referred to as a terminal equipment, a Mobile Station (MS), aMobile Terminal (MT), a User Terminal (UT), a Subscriber Station (SS), awireless device, a Personal Digital Assistant (PDA), a wireless modem, ahandheld device, etc. The BS refers to a fixed station communicatinggenerally with UEs and/or other BSs and exchanges data and controlinformation with the UEs and other BSs. The BS may be referred to as anevolved-NodeB (eNB), a Base Transceiver System (BTS), an Access Point, aProcessing Server (PS), etc.

A cell area in which a ES provides a service may be divided into aplurality of subareas in order to improve system performance. Each ofthe plurality of subareas may be referred to as a sector or a segment. Acell identity (Cell ID or IDCell) is assigned based on a total system,whereas a sector or segment identity is assigned based on a cell area inwhich the ES provides a service. Generally, a UE is distributed in awireless communication system and may be fixed or mobile. Each UE maycommunicate with one or more ESs through Uplink (UL) or Downlink (DL) ata given time.

The present invention may be applied to various types of multi-nodesystems. For example, the embodiment is of the present invention may beapplied to a Distributed Antenna. System (DAS), a macro node having lowpower Radio Remote Heads (RRHs), a multi-BS cooperative system, apico-/femto-cell cooperative system, and a combination thereof. In amulti-node system, one or more BSs connected to a plurality of nodes maycooperate with each other to simultaneously transmit signals to a UE orto simultaneously receive signals from the UE.

A DAS uses, for communication, a plurality of distributed antennasconnected to one BS or one BS controller for managing a plurality ofantennas located at a prescribed interval in an arbitrary geographicarea. (called a cell) through a cable or a dedicated line. In the DAS,each antenna or each antenna group may be one node of a multi-nodesystem of the present invention. Each antenna of the DAS may operate asa subset of antennas included in one BS or one BS controller. Namely,the DAS is a kind of the multi-node system and a distributed antenna orantenna group is a kind of a node in a multi-antenna system. The DAS isdistinguished from a Centralized. Antenna System (CAS) having aplurality of antennas centralized at the center of a cell, in that aplurality of antennas included in the DAS is distributed at a prescribedinterval in a cell. The DAS is different from a femto-/pico-cellcooperative system in that one BS or one BS controller manages alldistributed antennas or distributed antenna groups located in a cell atthe center of the cell, rather than each antenna unit manages an antennaarea. The DAS is also different from a relay system or an ad-hoc networkthat uses a BS connected wirelessly to a relay station in thatdistributed antennas are connected to each other through a cable or adedicated line. Moreover, the DAS is distinguished from a repeater thatsimply amplifies a signal and transmits the amplified signal in that adistributed antenna or a distributed antenna group can transmit a signaldifferent from a signal transmitted by other distributed antennas orother distributed antenna groups to a UE located around thecorresponding antenna or antenna group according to a command of a BS ora BS controller.

Nodes of a multi-BS cooperative system or femto-/pico-cell cooperativesystem operate as independent BSs and cooperate with one another.Accordingly, each BS of the multi-BS cooperative system orfemto-/pico-cell cooperative system may be a node in a multi-node systemof the present invention. Multiple nodes of the multi-BS cooperativesystem or femto-/pico-cell cooperative system are connected to oneanother through a backbone network and perform cooperativetransmission/reception by performing scheduling and/or handovertogether. In this way, a system in which a plurality of BSs participatesin cooperative transmission is referred to as a Coordinated Multi-Point(CoMP) system.

There are differences between various types of multi-node systems suchas a DAS, a macro node having low power PRHs, a multi-BS cooperativesystem, and a femto-/pico-cell cooperative system. However, since themulti-node system is different from a single-node system (e.g. a CAS,conventional MIMO system, a conventional relay system, and aconventional repeater system) and a plurality of nodes of the multi-nodesystem participates in providing a communication service to UEs throughcooperation, the embodiments of the present invention can be applied toall types of multi-node systems. For convenience of description, thepresent invention will describe a DAS by way of example. However, thefollowing description is purely exemplary. Since an antenna or anantenna group of a DAS may correspond to a node of another multi-nodesystem and a BS of the DAS corresponds to one or more cooperative BSs ofanother multi-node system, the present invention is applicable to othermulti-node systems in a similar way.

FIG. 1 illustrates the structure of a DAS to which the present inventionis applied. Specifically, FIG. 1 illustrates the structure of a systemin the case where the DAS is applied to a CAS using conventionalcell-based multiple antennas.

Referring to FIG. 1, a plurality of Centralized Antennas (CAs) havingsimilar path loss effects due to a very short antenna interval relativeto a cell radius may be located in an area adjacent to a BS. Inaddition, a plurality of Distributed Antennas (DAs) separated from eachother by a predetermined distance or more and having different path losseffects due to a wider antenna interval than the CAs may be located in acell area.

One or more DAs connected by wire to the BS are configured. The DA hasthe same meaning as an antenna node for use in a DAS or as an antennanode. One or more DAs constitute one DA group to form a DA zone.

The DA group includes one or more DAs. The DA group may be variablyconfigured according to the location or signal reception state of a UEor may be fixedly configured to a maximum antenna number used in MIMO.The DA group may be called an antenna group. The DA zone is defined as arange within which antennas forming a DA group can transmit or receivesignals. The cell area shown in FIG. 1 includes n DA zones. A UEbelonging to a DA zone may perform communication with one or more DAsconstituting the DA zone. A BS simultaneously uses DAs and CAs whiletransmitting signals to a UE belonging to a DA zone, thereby raisingtransmission rate.

FIG. 1 illustrates a DAS applied to a CAS structure using conventionalmultiple antennas so that a BS and a UE can use the DAS. Although thelocations of CAs and DAs are distinguished for brevity of description,the present invention is not limited thereto and the CAs and DAs arevariously located according to implementation form.

As illustrated in FIG. 1, antennas or antenna nodes supporting each UEmay be limited. Especially, during DL data transmission, different datafor each antenna or antenna node may be transmitted to different UEsthrough the same time and frequency resources. This may be interpretedas a sort of MU-MIMO operation of transmitting different data streamsper antenna or antenna node through selection of an antenna or antennanode.

In the present invention, each antenna or antenna node may he an antennaport. The antenna port is a logical antenna implemented by one physicaltransport antenna or a combination of a plurality of physical transportantennas In the present invention, each antenna or antenna node may alsobe a virtual antenna. In a beamforming scheme, signal transmitted by oneprecoded beam may be recognized as a signal transmitted by one antennaand the one antenna transmitting the precoded beam is called a virtualantenna.

In the present invention, antennas or antenna nodes may be distinguishedby a reference signal (pilot). An antenna group including one or moreantennas that transmit the same reference signal or the same pilotrefers to a set of one or more antennas that transmit the same referencesignal or pilot. That is, each antenna or antenna node of the presentinvention may be interpreted as a physical antenna, a set of physicalantennas, an antenna port, a virtual antenna, or an antennadistinguished by a reference signal/pilot. In the embodiments of thepresent invention to be described later, an antenna or antenna node mayrepresent any one of a physical antenna, a set of physical antennas, anantenna port, a virtual antenna, and an antenna distinguished by areference signal/pilot. Hereinafter, the present invention will beexplained by referring to a physical antenna, a set of physicalantennas, an antenna port, a virtual antenna, or an antennadistinguished by a reference signal/pilot as an antenna or antenna node.

Referring to FIG. 2, a radio frame used in 3GPP LTE/LTE-A systems is 10ms (327, 200T_(s)) in duration and includes 10 equally-sized subframes,each subframe being 1 ms long. Each subframe includes two slots, each0.5 ms in duration. Here, T_(s) represents a sampling time and is givenas T_(s)=1/(2, 04.8×15 kHz). A slot includes a plurality of OrthogonalFrequency Division Multiplexing Access (OFDMA) symbols in the timedomain and a plurality of Resource Blocks (RBs) in the frequency domain.An RB includes a plurality of subcarriers in the frequency domain. AnOFDMA symbol may he called an OFDM symbol or an SC-FDMA symbol accordingto a multiple access scheme. The number of OFDMA symbols included in oneslot may vary according to channel bandwidth or the length of a CyclicPrefix (CP). For example, in a normal CP, one slot includes 7 OFDMAsymbols, whereas in an extended CP, one slot includes 6 OFDMA symbols.In FIG. 2, although a subframe in which one slot includes 7 OFDMAsymbols is illustrated for convenience of description, the embodimentsof the present invention to be described later are applicable to othertypes of subframes in a similar way. For reference, a resource composedof one OFDMA symbol and one subcarrier called a Resource Element (RE) inthe 3GPP DTE/LTE-A systems.

In the 3GPP LTE/LTE-A systems, each subframe includes a control regionand a data region. The control region includes one or more OFDMA symbolsstarting from the first OFDMA symbol. The size of the control region maybe independently configured for each subframe. A PCFICH, a PhysicalHybrid automatic repeat request (ARQ) Indicator Channel (PHICH) as wellas a PDCCH may be allocated to the control region.

As shown in FIG. 2, control information is transmitted to a UE usingpredetermined time and frequency resources among radio resources.Control information for UEs is transmitted together with MAP informationin control channel. Each UE searches for and then receives a controlchannel thereof among control channels transmitted by a BS. Resourcesoccupied by control channels inevitably increase as the number of UEswithin a cell increases. If Machine to Machine (M2M) communication and aDAS are actively used, the number of UEs in a cell will furtherincrease. Then, control channels for supporting the UEs also increase.Namely, the number of OFDMA symbols and/or the number of subcarriersoccupied by Control channels in one subframe increase inevitably.Accordingly, the present invention provides methods for efficientlyusing a control channel using the characteristic of a DAS.

In accordance with current CAS-based communication standards, allantennas belonging to one BS transmit control channels (e.g. MAP, A-MAP,PDCCH etc.) for all UEs in the BS in a control region. To obtain controlinformation such as information about an antenna node allocated to a UEand DL/UL resource allocation information, each UE should acquirecontrol information thereof by processing the control region which is acommon region scheduled for control information transmission. Forinstance, the UE should obtain control information thereof among signalstransmitted through the control region by applying a scheme such asblind decoding.

According to current communication standards, if all antennas transmitcontrol information for all UEs in the same control region, since allantennas transmit the same signal in the control region, implementationis easy. However, if the size of control information to be transmittedincreases due to factors such as increase in the number of UEs that theBS should cover, MU-MIMO operation, and additional control information(e.g. information on an antenna node allocated to the. UE) for a DAS,the size or number of control channels increases and thus it may bedifficult to transmit all control information using an existing controlregion.

FIG. 3 illustrates a UL subframe structure in a 3GPP system.

Referring to FIG. 3, a 1-ms subframe 500, a basic unit for LTE ULtransmission, includes two 0.5-ms slots 501. On the assumption of anormal CP, each slot has 7 symbols 502, each symbol corresponding to anSC-FDMA symbol. An RB 503 is a resource allocation unit defined as 12subcarriers in the frequency domain and one slot in the time domain. TheLTE UL subframe is largely divided into a data region 504 and a controlregion 505. The data region 504 refers to communication resources usedto transmit data such as voice data and packets and includes a PhysicalUplink Shared Channel (PUSCH). The control region 505 refers tocommunication resources used for each UE to transmit a DL channelquality report, an ACK/NACK for a received DL signal, and a ULscheduling request and includes a Physical Uplink Control Channel(PUCCH). A Sounding Reference Signal (SRS) is transmitted in the lastSC-FDMA symbol of a subframe in the time domain and in a datatransmission band in the frequency domain SRSs transmitted in the lastSC-FDMA symbol of the same subframe from a plurality of UEs can bedistinguished by their frequency positions/sequences.

Hereinbelow, description will be given of RB mapping. A PhysicalResource Block (PRB) and a Virtual Resource Block (VRB) are defined. ThePRB is configured as illustrated in FIG. 3. In other words, the PRB isdefined as N_(symb) ^(DL) contiguous OFDM symbols in the time domain andN_(sc) ^(RB) contiguous subcarriers in the frequency domain. PRBs arenumbered from 0 to N_(RB) ^(DL)−1 in the frequency domain. Therelationship between a PRB number n_(PRB) and an RE (k,l) in a slot isgiven by Equation 1.

$\begin{matrix}{n_{PRB} = \left\lfloor \frac{k}{N_{sc}^{RB}} \right\rfloor} & \left\lbrack {{Equation}\mspace{14mu} 1} \right\rbrack\end{matrix}$

where k denotes a subcarrier index and N_(sc) ^(RB) denotes the numberof subcarriers in an RB.

The VRB is equal in size to the PRB. A Localized VRB (LVRB) of alocalized type and a Distributed VRB (DVRB) of a distributed type aredefined. Irrespective of VRB type, a pair of VRBs with the same VRBnumber n_(VRB) is allocated over two slots of a subframe.

SRSs are transmitted in the last SC-FDMA symbol one subframe in the timedomain and in a data transmission band in the frequency domain. SRSstransmitted in the last SC-FDMA symbol of the same subframe from aplurality of UEs can be distinguished by frequency position.

A Demodulation Reference Signal. (DMRS) is transmitted in the middleSC-TDMA symbol of each slot in one subframe in the time domain and in adata transmission band in the frequency domain. For example, in asubframe to which a normal CP is applied, DMRSs are transmitted in the4th and 11th SC-FDMA symbols.

The DMRS may be associated with the transmission of a PUSCH or PUSCH.The SRS is a reference signal transmitted from a UE to a ES for ULscheduling. The BS estimates a UL channel through the received SRS anduses the estimated UL channel for UL scheduling. The SRS is notassociated with the transmission of a PUSCH or PUCCH. The same kind ofbasic sequence may be used for the DMRS and the SRS. Meanwhile, in ULmulti-antenna transmission, precoding applied to the DMRS may he thesame as precoding applied to the PUSCH.

The BS informs the UE of demodulation pilot information such as DMRSinformation of the BS so that the UE can directly measure a channel. TheDMRS information includes a sequence, an RB type, an allocated resourcetype, a port position, the number of beams, or the number of ranks.Accordingly, the UE can obtain a PDSCH signal corresponding to a PDCCHthrough the PDCCH by use of the DMRS information.

A reference signal, especially, a DMRS sequence for a PUSCH may bedefined by Equation 2.

r _(n) _(s) (m)=1/√2(1−2·c(2m))+j1/√2(1−2·c(2m+1)), m=0,1, . . . 12N_(RB) ^(PDSCH)−1   [Equation. 2]

Referring to Equation 2, a UE-specific reference signal r_(r) _(s) (m)for port 5 has a value between −1 and 1 by the difference between c(2m)c(2m+1) and 1, A QPSK normalization value according to an average powervalue can be obtained by 1/√2. In Equation 2, c(i) denotes apseudo-random sequence which is a PN sequence and may he defined by alength-31 Gold sequence. Equation 3 indicates an example of a Goldsequence c(n).

c _(init)=(└n _(s)/2┘+1)·(2N _(ID) ^(cell)+1)·2¹⁶ +n _(RNTI)  [Equation. 3]

where n_(RNTI) denotes a UE-specific unique I.D.

Reference signals for other ports 7, 8, 9, and 10 may be defined byEquation 4.

$\begin{matrix}{{{r(m)} = {{\frac{1}{\sqrt{2}}\left( {1 - {2 \cdot {c\left( {2m} \right)}}} \right)} + {j\frac{1}{\sqrt{2}}\left( {1 - {2 \cdot {c\left( {{2m} + 1} \right)}}} \right)}}},{m = \left\{ \begin{matrix}{0,1,\ldots \mspace{11mu},{{12N_{RB}^{\max,{DL}}} - {1\mspace{14mu} {normal}\mspace{14mu} {cyclic}\mspace{14mu} {prefix}}}} \\{0,1,\ldots \mspace{11mu},{{16N_{RB}^{\max,{DL}}} - {1\mspace{14mu} {extended}\mspace{14mu} {cyclic}\mspace{14mu} {prefix}}}}\end{matrix} \right.}} & \left\lbrack {{Equation}\mspace{14mu} 4} \right\rbrack\end{matrix}$

In Equation 4, c(i) denotes a pseudo-random sequence, which is a PNsequence, and may be defined by a length-31 Gold sequence. Equation 5indicates an example of the gold sequence c(n).

c _(init)=(└n _(s)/2┘+1)·(2N _(ID) ^(cell)+1)·2¹⁶ +n _(SCID)   [Equation5]

where C_(init) denotes an initial sequence, n_(s) denotes a slot numberin one radio frame, N_(ID) ^(cell) denotes a virtual cell ID, n_(SCID)denotes a UE-specific unique ID for antenna ports 7 and 8 and may bedefined by the following Table 1. Accordingly, n_(SCID) has a value of 0or 1 and is transmitted as 1-bit signaling.

TABLE 1 Scrambling identity field in DCI format 2B or 2C [3] n_(SCID) 00 1 1

As described above, n_(RNTI) or n_(SCID) is a value determined initiallyin a connection process between the UE and the BS.

A PDCCH indicates a control channel allocated to a DL subframe. In asystem of 3GPP Rel-11 or more, introduction of a multi-node systemincluding a plurality of access nodes in cell has been determined forperformance improvement (here, the multi-node system includes a DAS, anRRH, etc. and will be collectively referred to as an RRH hereinbelow).Standardization tasks for applying various MIMO schemes and cooperativecommunication schemes, that are being developed or are applicable in thefuture, to a multi-node environment is under way. Basically, althoughimprovement of link quality is expected because various communicationschemes such as a localized or cooperative scheme for each UE/BS can beapplied due to the introduction of an RRH, the immediate introduction ofa new control channel is needed in order to apply the above-mentionedvarious MIMO schemes and cooperative communication schemes to themulti-node environment. Due to such necessity, a control channelmentioned newly as a channel to he introduced is an Enhanced-PDCCH(E-PDCCH) (an RRH-PDCCH and an x-PDCCH are collectively referred to asan e-PDCCH) and a data transmission region (hereinafter, referred to asa PDSCH region) rather than a legacy control region (hereinafter,referred to as a PDCCH region)) is preferred as an allocation positionof the E-PDCCH. Consequently, it is possible for each UE to transmitcontrol information for a node through the e-PDCCH and thus a problemcaused by shortage of the legacy PDCCH region can be solved.

The legacy PDCCH is transmitted only using transmit diversity in aprescribed region and various schemes used for the PDSCH, such asbeamforming, MU-MIMO, best band selection, etc., have not been appliedto the legacy PDCCH. For this reason, the PDCCH functions as abottleneck of system performance and improvement of this problem hasbeen required. In the middle of discussing the new introduction of anRRH for system performance improvement, the necessity of a new PDCCH hasbeen emerged as a method for overcoming insufficient capacity of thePDCCH when cell IDs of RRHs are the same. To distinguish a PDCCH to benewly introduced from the legacy PDCCH, the PDCCH to be newly introducedis referred to as an. E-PDCCH. In the present invention, it is assumedthat the E-PDCCH is located in the PDSCH region.

FIG. 4 is a diagram illustrating an E-PDCCH and a PDSCH scheduled by theE-PDCCH.

Referring to FIG. 4, the E-PDCCH may use part of a PDSCH region thatgenerally transmits data. A UE should perform blind decoding to detectwhether an E-PDCCH thereof is present. Although the E-PDCCH performs ascheduling operation (i.e. PDSCH and PUSCH control) like the legacyPDCCH, if the number of UEs connected to a node such as an RRHincreases, a greater number of E-PDCCHs is allocated in the PDSCH regionand thus the number of blind decoding attempts to be performed by the USincreases, thereby raising complexity.

Meanwhile, an approach to reusing the structure of a legacy R-PDCCH isattempted as a detailed allocation scheme of the E-PDCCH. FIG. 5 is adiagram illustrating the structure of an R-PDCCH transmitted to a relaynode.

Referring to FIG. 5, only a DL grant is necessarily allocated to thefirst slot and a UL grant or a data PDSCH may be allocated to the secondslot. In this case, an R-PDCCH is allocated to data REe except for aPDCCH region, CRSs, and DMRSs. Both the DMRS and CRS may be used forR-PDCCH demodulation, and when the DMRS is used, port 7 and a ScramblingID (SCID) of 0 are used,

Meanwhile, when the CRS is used, port 0 is used only when the number ofPBCH transmit antennas is 1, and ports 0 and 1 and ports 0 to 3 are usedin transmit diversity mode when the number of PBCH transmission antennasis 2 and 4, respectively.

In a detailed allocation scheme of the E-PDCCH, reusing the structure ofthe legacy R-PDCCH means separate allocation of a DL grant and a ULgrant per slot. That is, the E-PDCCH has a structure following theR-PDCCH. This has an advantage that impact upon existing standard may berelatively insignificant by reusing a known structure.

In the present invention, such an allocation scheme is referred to asprior art 1).

FIG. 6 is a diagram illustrating exemplary allocation of an E-PDCCHaccording to prior art 1).

According to prior art 1), the E-PDCCH is allocated in such a mannerthat a DL grant is allocated to the first slot of a subframe and a ULgrant is allocated to the second slot of the subframe. Herein, it isassumed that the E-PDCCH is configured in both the first slot and thesecond slot of the subframe. The DL grant and UL grant are separatelyallocated to the E-PDCCH of the first slot and the E-PDCCH of the secondslot, respectively.

Since the DL grant and the UL grant that a UE should detect per slot ina subframe are separated from each other, the UE configures a searchregion in the first slot to perform blind decoding for detecting the DLgrant and configures a search region in the second slot to perform blinddecoding for detecting the UL grant.

Meanwhile, a current 3GPP LTE system has a Downlink Transmission Mode(DL TM) and an Uplink Transmission Mode (UL TM). One TM per UE isconfigured through upper layer signaling. In the DL TM, the number offormats of DL control information that each UE should search for perconfigured mode, i.e. DCI formats, is 2. In the UL TM, on the otherhand, the number of DCI formats that each UE should search for perconfigured mode is 1 or 2. For example, in UL TM 1, DL controlinformation corresponding to a UL grant includes DCI format 0 and, in ULTM 2, DL control information corresponding to the UL grant includes DCIformat 0 and DCI format 4. The DL TM is defined as one of mode 1 to mode9 and the UL TM is defined as one of mode 1 and mode 2.

Accordingly, the number of blind decoding attempts that should beperformed in DL grant and UL grant allocation regions in order for a UEto search for an E-PDCCH thereof in a UE-specific search region per slotas shown in FIG. 6 is as follows.

(1) DL grant=(number of candidate PDCCHs)×(number of DCI formats inconfigured DL TM)=16×2=32

(2) UL grant in UL TM 1=(number of candidate PDCCHs)×(number of DCIformats in UL TM 1)=16×1=16

(3) UL grant in UL TM 2=(number of candidate PDCCHs)×(number of DCIformats in UL TM 2)=16×2=32

(4) Total number of blind decoding attempts=number of blind decodingattempts in first slot+number of blind decoding attempts in second slot

-   -   UL TM 1: 32+16=48    -   UL TM 2: 32+32=64

Meanwhile, a method for simultaneously allocating both the DL grant andthe UL grant to the first slot has been proposed. For convenience ofdescription, this method is referred to as prior art 2).

FIG. 7 is a diagram illustrating exemplary allocation of an E-PDCCHaccording to prior art 2).

Referring to FIG. 7, the E-PDCCH is allocated in such a manner that theDL grant and the UL grant are simultaneously allocated to the first slotof a subframe. Especially, it is assumed in FIG. 7 that the E-PDCCH isconfigured only in the first slot of a subframe. Therefore, both the DLgrant and the UL grant are present in the E-PDCCH of the first slot andthe UE performs blind decoding for searching for the DL grant and the ULgrant only in the first slot of the subframe.

As mentioned previously, in the 3GPP LTE system, a DCI format to bedetected is determined according to a TM configured per UE. Especially,a total of two DCI formats per DL TM, i.e. DL grants, is determined andall DL TMs basically include DCI format IA to support a fallback mode.DCI format 0 among UL grants is equal to DCI format 1A in size andadditional decoding is not performed because it can be distinguishedthrough a 1-bit flag. However, for DCI format 4, which is the otherformat among the UL grants, additional blind decoding should beperformed.

Accordingly, the UE performs blind decoding in the same region as thelegacy PDCCH region and the number of blind decoding attempts thatshould be performed to search for the E-PDCCH in a UE-specific searchregion, i.e. the DL grant and the UL grant, is as follows.

(1) DL grant=(number of candidate PDCCHs)×(number of DCI formats inconfigured DL TM)=16×2=32

(2) UL grant in UL TM 1=(number of candidate PDCCHs)×(number of DCIformats in UL TM 1)=0

(3) UL grant in UL TM 2=(number of candidate PDCCHs)×(number of DCIformats in UL TM 2)=16×1−16

(4) Total number of blind decoding attempts

-   -   UL TM 1: 32+0=32    -   UL TM 2: 32+16=48

The present invention proposes a DL grant and UL grant allocation methodof an E-PDCCH. As previously described, although a main design method ofthe E-PDCCH can follow the structure of the legacy R-PDCCH, there may bevarious methods for allocating a DL grant and a UL grant per slot indesigning the E-PDCCH unlike the R-PDCCH.

Accordingly, the E-PDCCH, a DL control channel, has a pure FDM structureallocated only for the first slot. However, E-PDCCH allocation, which isbeing discussed, may he performed in a full FDM structure without beinglimited to one slot.

FIG. 8 illustrates exemplary cross-interleaving of the E-PDCCH.

Referring to FIG. 8, a method for multiplexing the E-PDCCH is used in amanner similar to an R-PDCCH multiplexing method. Under the state that acommon PRB set is configured, E-PDCCHs of a plurality of UEs areinterleaved in time and frequency domains. It can be confirmed in FIG. 8that an E-PDCCH of each UE is divided into several E-PDCCHs. Throughthis method, frequency/time diversity over a plurality of RBs can beobtained and thus advantages can be expected from the standpoint ofdiversity gain.

FIG. 9 illustrates exemplary allocation of an E-PDCCH to a resourceconfiguration region for cross interleaving or non-cross interleavingaccording to an exemplary embodiment of the present invention.

Referring to FIG. 9, a resource region for an E-PDCCH format that iscross-interleaved, (hereinafter, referred to as an interleaving region),and a resource region for an E-PDCCH format that is notcross-interleaved, (hereinafter, referred to as a non-interleavingregion), are configured. As another embodiment, a resource region for acommon search space and a resource region for a US-specific search spaceare configured. As a further embodiment, a resource region for a firstRNTI set among multiple RNTIs and a resource region for a second RMTIare configured. Since the resource region for the common search space iscommonly applied to UEs, it may be positioned in the cross interleavingregion. However, since UE-specific interleaving is not performed in thenon-interleaving region, a plurality of cell IDs may be used in thenon-interleaving ion. If the resource region of the E-PDCCH is comprisedof the interleaving region and non-interleaving region, a DMRSconfiguration method per region is different according tocharacteristics of each region. Since multiple E-PDCCHs may be mixed inthe interleaving region, the same antenna port and/or DMRS sequenceshould be configured. However, in the non-interleaving region, multipleantenna ports and/or DMRS sequences may be configured

Referring to FIG. 9, a resource region for E-PDCCH formats withcross-interleaving, (hereinafter, referred to as an interleavingregion), and a resource region for E-PDCCH formats withoutcrossing-interleaving, (hereinafter, referred to as a non-interleavingregion), are configured as an E-PDCCH resource region. As anotherembodiment, a resource region for a common search space and a resourceregion for a UE-specific search space may be configured. As a furtherembodiment, a resource region for a first RNTI set among multiple RNTIsand a resource region for a second RNTI may be configured. FIG. 9 showsan exemplary E-PDCCH region configured by the interleaving region andthe non-interleaving region. As an interleaving unit of the E-PDCCH,both the method shown in FIG. 8 for partially dispersing ControlChannel. Elements (CCEs) in an RB and an interleaving method on a slotbasis may be applied. To decode the E-PDCCH, a DMRS port suitable foreach region should be basically allocated and a corresponding DMRSsequence should also be configured. A Physical Cell ID (PCI) isbasically used for configuring the DMRS sequence. To multiplex theE-PDCCH, it may be additionally considered that a CSI-RS configuredinstead o f the PCI or a flexible PCI is configured using dedicatedsignaling.

FIG. 10 conceptually illustrates a first CCE index n_(CCE). A PUCCHresource allocation method of a legacy 3GPP Rel-10 is shown.

In a current 3GPP LTE system, an ACK/NACK of a PDSCH is transmittedthrough a PUCCH which is a UL control channel. In this case, informationtransmitted through the PUCCH varies according to format. This issummarized as follows.

In the LTE system, a PUCCH resource for ACK/NACK is not pre-allocated toeach. US and a plurality of UEs in a cell uses a plurality of PUCCHresources separately at each time point. Specifically, the PUCCHresource used by the US to transmit ACK/NACK is implicitly determinedbased on a PDCCH carrying scheduling information for a PDSCH carrying DLdata. An entire, region in which the PDCCH is transmitted in a DLsubframe is comprised of a plurality of CCEs and the PDCCH transmittedto the UE is comprised of one or more CCEs. A CCE includes plural (e.g.9) Resource Element Groups (REGs). One REG includes four neighboring REsexcept for an RS. The US transmits ACK/NACK through an implicit PUCCHresource induced or calculated by a function of a specific CCE index(e.g. the first or lowest CCE index) among CCE indexes constituting thePDCCH received thereby.

Referring to FIG. 10, each PUCCH resource index corresponds to a PUCCHresource for an. ACK/NACK. For example, assuming that schedulinginformation for a PDSCH is transmitted to the US through a PDCCHincluding CCE indexes 4 to 6, the UE transmits ACK/NACK to a BS througha PUCCH induced or calculated from the lowest CCE index for example,through a PUCCH index 4.

PUCCH formats 1a/1b may transmit information about ACK NACK, PUCCHformats 2/2a/2b may transmit information about CQI and about the CQI andACK/NACK, and a PUCCH format 3 may transmit information about multipleACKs/NACKs.

In this case, PUCCH resource indexes n_(PUCCH) ⁽¹⁾ and n_(PUCCH) ⁽²⁾ aredefined and PUCCH resource allocation is performed using the PUCCHresource indexes according to format.

n_(PUCCH) ⁽¹⁾ is a resource index for PUCCH formats 1/1a/1b andn_(PUCCH) ⁽²⁾ is a resource index for PUCCH formats 2/2a/2b. A resourceallocation method using the two parameters n_(PUCCH) ⁽¹⁾ and n_(PUCCH)⁽²⁾ is as follows.

First, n_(PUCCH) ⁽¹⁾ and n_(PUCCH) ⁽²⁾ are determined. n_(PUCCH) ⁽¹⁾ isdetermined as follow.

A Semi-Persistent Scheduled (SPS)-UE and a scheduling request may bedesignated through RRC signaling and a resource index for, for example,PUCCH formats 1/1a/1b may be determined by Equation 6.

n _(PUCCH) ⁽¹⁾ =n _(CCE) +n _(PUCCH) ⁽¹⁾   [Equation 6]

where n_(PUCCH) ⁽²⁾ denotes a PUCCH resource index for ACK/NACKtransmission, n_(PUCCH) ⁽¹⁾ denotes the number of CCEs in a PUCCH, whichis a signaling value received from a higher layer as indicated byEquation 7, and n_(CCE) denotes the first CCE index of a PDCCH which isthe lowest value among CCE indexes used for PDCCH transmission.

$\begin{matrix}{{N_{PUCCH}^{(1)} = {c \cdot {N_{sc}^{RB}/\Delta_{shift}^{PUCCH}}}},{c = \left\{ {\begin{matrix}3 & {{normal}\mspace{14mu} {cyclic}\mspace{14mu} {prefix}} \\2 & {{extended}\mspace{14mu} {cyclic}\mspace{14mu} {prefix}}\end{matrix},{N_{sc}^{RB} = 12},{\Delta_{shift}^{PUCCH} \in \left\{ {1,2,3} \right\}}} \right.}} & \left\lbrack {{Equation}\mspace{14mu} 7} \right\rbrack\end{matrix}$

n_(PUCCH) ⁽²⁾ is UE-specifically, semi-statically determined by RRCsignaling as indicated by Equation 6 and denotes a parametercqi-PUCCH-ResourceIndex included in an CQI-ReportConfig RRC message.

Second, an orthogonal sequence index and a cyclic shift are determinedusing the determined n_(PUCCH) ⁽¹⁾ and n_(PUCCH) ⁽²⁾. Third, referringto FIG. 11, a physical resource for the PUCCH resource index isallocated.

FIG. 11 illustrates physical mapping of a. PUCCH format to a PUCCHresource block or region.

An RB index m allocated to a physical region according to n_(PUCCH) ⁽¹⁾,and n_(PUCCH) ⁽²⁾ per UE is calculated. A PUCCH resource is allocatedfrom the edge of the PUCCH resource region starting from PUCCH format 2.A region to which a mixed format of formats 1/1a/1b and 2/2a/2b isallocated is only one. Formats 1/1a/1b are allocated to an inner side ofthe PUCCH resource. The PUCCH formats are allocated by a slot hopping(RB unit) scheme in one subframe.

FIG. 12 illustrates the relationship between a PUCCH resource index anda physical RB index m.

The allocation relationship between a PUCCH resource index and a mappedphysical RB in a logical domain allocated per UE is as follows.

Referring to FIG. 12, a system parameter includes cyclic shift value, anormal CP, etc. The cyclic shift value is Δ_(shift) ^(PUCCH)=1 and mayhave a value up to 12. A normal CP is c=3, n_(PUCCH) ⁽¹⁾ is n_(PUCCH)⁽¹⁾c·N_(sc) ^(RB)/Δ_(shift) ^(PUCCH)=36, and bandwidth for PUCCH formats2/2a/2b is n_(RB) ⁽²⁾=2·N_(sc) ^(RB)=2·N_(sc) ^(RB)=24. In addition, thenumber of cyclic shifts for PUCCH formats 1/1a/1b in a mixed RB offormats 1/1a/1b and 2/2a/2b is N_(sc) ⁽¹⁾=7.

In the present invention, a PUCCH resource allocation method forACK/NACK transmission of a PDSCH scheduled from an E-PDCCH is provided.For ACK/NACK transmission of the PDSCH scheduled from the E-PDCCH, a‘CCE index’ for PUCCH resource allocation is needed. Namely, PUCCHresource allocation is performed by the above Equation 6.

However, since the E-PDCCH is transmitted in a region different from aregion in which a legacy PDCCH is transmitted, a CCE index correspondingto the E-PDCCH should be defined. The CCE index of the E-PDCCH forresource allocation for transmitting ACK/NACK to the PUCCH is defined asan enhanced CCE (eCCE) index. The eCCE index may be configured in theunit of an E-PDCCH set.

In the present invention, although the E-PDCCH region is separatelydescribed as an ‘interleaving region’ and a ‘non-interleaving region’,an application example thereof is not limited. Hereinafter, aninterleaving region for the E-PDCCH is referred to as a ‘first region’and a non-interleaving region for the E-PDCCH is referred to as a‘second region’. A description will first be given of the case in whicha PUCCH resource is commonly used between the E-PDCCH and a legacyPDCCH.

FIG. 13 illustrates search space concatenation based on N_(CCE)according to the present invention.

As a first proposal of the present invention, a final CCE index isinduced by adding a total number of CCEs of a legacy PDCCH to a firstCCE index of an E-PDCCH in the first region and a PUCCH resource forACK/NACK transmission is allocated using the final CCE index. In thiscase, a UE may semi-statically specify the PUCCH resource for ACK/NACKtransmission in the unit of each. E-PDCCH set by a PUCCH resource startoffset. The eCCE may be used to employ a dynamic or non-dynamic PUCCHresource offset by the E-PDCCH.

In the first proposal, the eCCE, which is a CCE index of an E-PDCCH inthe first region, is determined separately from a legacy PDCCH region.Namely, operation for detecting the first CCE index of the E-PDCCH isidentical to operation for detecting a CCE index in a legacy release-10LTE system. However, if the CCE index of the E-PDCCH is overlapped withthe CCE index of the legacy PDCCH, PDCCH resources may collide.Therefore, as shown in FIG. 13, the CCE index n_(CCE) ^(R1) of theE-PDCCH is assigned after the CCE indexes of the legacy PDCCHs as givenby Equation 8 in order to protect the ACK/NACK transmission of thelegacy PDCCH.

n _(PUCCH) ^((1,p=p) ⁰ ⁾ =n _(CCE) ^(R1) +N _(CCE) +N _(PUCCH) ⁽¹⁾  [Equation 8]

In order for the UE to obtain information about a total number of CCEsof the legacy PDCCH, N_(CCE), the following UE operation may beadditionally defined.

In the present invention, if the UE monitors the legacy PDCCH region,the UE itself calculates N_(CCE) and, if not, N_(CCE) is signaled to theUE. In this case, N_(CCE) may be the number of CCEs of an actual legacyPDCCH or may be a value signaled after the BE arbitrarily determines amaximum number of CCEs for long-term signaling.

If a PUCCH resource between the E-PDCCH and the legacy PDCCH isseparately used, a PUCCH resource for ACK/NACK transmission may heallocated using the first CCE index of the E-PDCCH without considering atotal number of CCEs of the legacy PDCCH, N_(CCE), as indicated byEquation 9.

N _(PUCCH) ^(l, p=p) ^(c) ⁾ =n _(CCE) ^(R1) +N _(PUCCH) ⁽¹⁾   [Equation9]

In a second proposal of the present invention, the lowest RE index ofthe E-PDCCH or a PDSCH scheduled through the E-PDCCH is defined as afirst CCE index in the second region and a PUCCH resource for ACK/NACKtransmission is allocated using the first CCE index.

In the second proposal, an ACK/NACK resource cannot be mapped because itis impossible to allocate the CCE index to the E-PDCCH. Accordingly, areference value which can replace the first CCE index of the E-PDCCHshould be defined. To this end, the UE may use the lowest RB index(considering an aggregation level) detecting the E-PDCCH or the lowestRB index scheduled through the E-PDCCH as the first CCE index. However,since such operation may generate collision in PUCCH resource allocationwhen the CCE index is overlapped with a CCE index of the legacy PUCCH,it is desirable to allocate the PUCCH resource after N^(CCE) of thePDCCH as indicated by Equation 10 as in the first proposal.

n _(PUCCH) ^((i, p=p) ⁰ ⁾ =n _(CCE) ^(R2) +N _(CCE) +n _(PUCCH) ⁽¹⁾  [Equation 10]

To obtain a total number of CCEs of the legacy PDCCH, N_(CCE), thefollowing UE operation may be additionally defined.

In the second proposal, if the UE monitors the legacy PDCCH region, theUE itself calculates N_(CCE) and, if not, N_(CCE) is signaled to the UE.

If ACK/NACK resources collide due to sharing of the PUCCH resourcebetween the first region and the second region, the PUCCH resource forACK/NACK transmission can be allocated using a total number of CCEs ofthe first region and the CCE index (or the lowest RB index) of theE-PDCCH of the second region.

In a situation in which the E-PDCCH of the first region and the E-PDCCHof the second region are simultaneously mapped to an ACK/NACK region ofthe legacy PDCCH, ACK/NACK mapping may collide due to repetitive CCEindexes between E-PDCCHs. In this case, collision of the ACK/NACKresource can be prevented through allocation of the CCE index of thesecond region after a total number of CCEs of the first region, N_(CCE)^(R1), indicated by Equation 11. Accordingly, the CCE index of the E-PDCCH is determined by further considering the total number of CCEs ofthe first region.

n _(PUCCH) ^((l, p=p) ⁰ ⁾ =n _(CCE) ^(R2) +N _(CCE) ^(R1) +N _(CCE) +N_(PUCCH) ⁽¹⁾   [Equation 11]

However, when the PUCCH resource is separately used between all E-PDCCHregions and the legacy PDCCH, the first CCE index of the E-PDCCH is usedto allocate the PUCCH resource for ACK/NACK transmission. Accordingly,in this case, the CCE index of the E-PDCCH may be determined asindicated by Equation 12 without considering a total number of CCEs ofthe first region, N_(CCE) ^(R1), and a total number of CCEs of thelegacy PDCCH, N_(CCE).

n _(PUCCH) ^((l, p=p) ⁰ ⁾ =n _(CCE) ^(R2) +N _(PUCCH) ⁽¹⁾   [Equation12]

When a plurality of UEs simultaneously uses the lowest RE index as a CCEindex, collision can be prevented using an offset value.

If two or more UEs simultaneously configure a CCE index using the samelowest RB index (MU-MIMO transmission), the same CCE index may bedifferently configured using an offset value. The offset value may use aDMRS port, UE. RNTI, etc. used when the US detects the E-PDCCH.Therefore, in localized E′-PDCCH allocation, an antenna port of theE-PDCCH (i.e. DMRS port) or an antenna port of the PDSCH may be usedinstead of the lowest eCCE index.

As a third proposal of the present invention, a PUCCH region for theE-PDCCH may be configured in an ACK/NACK region of the legacy PUCCH and,in this case, additional signaling to the US may be performed. Namely,the eCCE indexed per E-PDCCH set may be signaled and the PUCCH resourceincluding ACK/NACK of the PDSCH scheduled to the E-PDCCH may besemi-statically configured through signaling. The PUCCH resource may bedynamically/non-dynamically configured. Signaling is not limited to RRCsignaling.

FIG. 14 illustrates separate configuration of a PUCCH ACK/NACK resourcefor an E-PDCCH according to the present invention.

An ACK/NACK resource of the E-PDCCH may be configured by a separatePUCCH resource as shown in FIG. 14 and only ACK/NACK of the E-PDCCH isallocated and transmitted in a corresponding region. Conversely, thePUCCH resource of the E-PDCCH may be configured without distinguishingit from the legacy PDCCH. The UE should recognize PUCCH configurationinformation to map ACK/NACK of a scheduled PDSCH to the PUCCH. The PUCCHACK/NACK configuration information may be directly transmitted to the UNusing RRC signaling or dynamic signaling or the UN may implicitlyrecognize the PUCCH configuration information using a cell ID (PCI orvirtual PCI), CSI-RS configuration (port/sequence configuration)information, and DMRS configuration (port/sequence configuration)information.

An additional PUCCH resource for the E-PDCCH is configured and the firstregion and the second region are separately configured even in acorresponding region.

In the third proposal of the present invention, if the first region andthe second region are separately configured, Equation 9 or Equation 12in the case in which the region of the first proposal and the region ofthe second proposal are separated may be identically applied. Namely,since collision does not occur in PUCCH ACK/NACK resource mapping perregion, legacy operation for allocating legacy PUCCH ACK/NACK may beidentically reused.

In proposal 3-2 of the present invention, the first region and thesecond region are simultaneously configured in the additional PUCCHresource for the E-PDCCH.

In the proposal 3-2 of the present invention, the above-mentioned firstproposal and second proposal may be applied or may be oppositelyapplied. Namely, since collision may occur in PUCCH ACK/NACK mappingbetween the first region and the second region, collision of theACK/NACK resource may be prevented in consideration of a total number ofACK/NACK resources or a total number of CCEs of each region.

FIG. 15 illustrates a ES and a US which are applicable an exemplaryembodiment of the present invention.

The US may operate as a transmitter in UL and as a receiver in DL.Conversely, the ES may operate as a receiver in UL and as a transmitterin DL,

Referring to FIG. 15, a radio communication system includes a BS 110 anda UE 120. The BS 110 includes a processor 112, a memory 114, and a RadioFrequency (RF) unit 116. The processor 112 may be configured toimplement the procedures and/or methods proposed in the presentinvention. The memory 114 is connected to the processor 112 and storesinformation related to operation of the processor 112. The RF unit 116is connected to the processor 112 and transmits and/or receives RFsignals. The US 120 includes a processor 122, a memory 124, and an RFunit 126. The processor 122 may be configured to implement theprocedures and/or methods proposed in the present invention. The memory124 is connected to the processor 122 and stores information related tooperation of the processor 122. The RF unit 126 is connected to theprocessor 122 and transmits and/or receives RF Signals. The BS 110and/or the UE 120 may have a single antenna or multiple antennas.

The above-described embodiments are combinations of constituent elementsand features of the present invention in a predetermined form. Theconstituent elements or features should be considered selectively unlessotherwise mentioned. Each constituent element or feature may bepracticed without being combined with other constituent elements orfeatures. Further, the embodiments of the present invention may beconstructed by combining partial constituent elements and/or partialfeatures. Operation orders described in the embodiments of the presentinvention may be rearranged. Some constructions or features of any oneembodiment may be included in another embodiment or may be replaced withcorresponding constructions or features of another embodiment. It isapparent that the embodiments may be constructed by a combination ofclaims which do not have an explicitly cited relationship in theappended claims or may include new claims by amendment afterapplication.

The embodiments of the present invention may be achieved by variousmeans, for example, hardware, firmware, software, or a combinationthereof. In a hardware configuration, the exemplary embodiments of thepresent invention may be achieved by one or more Application SpecificIntegrated Circuits (ASICs), Digital Signal Processors (DSPs), DigitalSignal Processing Devices (DSPDs), Programmable Logic Devices (PLDs),Field Programmable Gate Arrays (FPGAs), processors, controllers,microcontrollers, microprocessors, etc.

In a firmware or software configuration, the exemplary embodiments ofthe present invention may be achieved by a module, a procedure, afunction, etc. performing the above-described functions or operations.Software code may be stored in a memory unit and executed by aprocessor. The memory unit may be located at the interior or exterior ofthe processor and may transmit and receive data to and from theprocessor via various known means.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the present inventionwithout departing from the spirit or scope of the invention. Thus, it isintended that the present invention cover the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

INDUSTRIAL APPLICABILITY

The present invention may be used for a UE, a BS, or other equipment ofa wireless communication system. Specifically, the present invention maybe used for a multi-node system that provides a communication service toa UE through a plurality of nodes.

What is claimed is:
 1. A method for transmitting an uplink controlchannel to a base station by a user equipment in a wirelesscommunication system, the method comprising: determining a specificuplink resource based on at least one parameter for a downlink controlchannel; and transmitting the uplink control channel using the specificuplink resource to the base station, wherein the at least one parameterfor the downlink control channel includes a value derived from anantenna port index of a demodulation reference signal associated withthe downlink control channel.
 2. The method of claim 1, wherein the atleast one parameter comprises one of downlink resource indexesassociated with the downlink control channel.
 3. The method of claim 1,wherein the downlink control channel is demodulated using thedemodulation reference signal.
 4. The method of claim 1, wherein theuplink control channel carries the ACK/NACK information for a downlinkshared channel scheduled by the downlink control channel.
 5. A userequipment in a wireless communication system, the user equipmentcomprising: a processor configured to determine a specific uplinkresource based on at least one parameter for a downlink control channel;and a radio frequency (RF) module configured to transmit the uplinkcontrol channel using the specific uplink resource to a base station,wherein the at least one parameter for the downlink control channelincludes a value derived from an antenna port index of a demodulationreference signal associated with the downlink control channel.
 6. Theuser equipment of claim 5, wherein the at least one parameter comprisesone of downlink resource indexes associated with the downlink controlchannel.
 7. The user equipment of claim 5, wherein the downlink controlchannel is demodulated using the demodulation reference signal.
 8. Theuser equipment of claim 5, wherein the uplink control channel carriesthe ACK/NACK information for a downlink shared channel scheduled by thedownlink control channel.
 9. A method for receiving an uplink controlchannel from a user equipment at a base station in a wirelesscommunication system, the method comprising: receiving the uplinkcontrol channel using a specific uplink resource, wherein the specificuplink resource is determined based on at least one parameter for adownlink control channel, wherein the at least one parameter for thedownlink control channel includes a value derived from an antenna portindex of a demodulation reference signal associated with the downlinkcontrol channel.
 10. The method of claim 9, wherein the at least oneparameter comprises one of downlink resource indexes associated with thedownlink control channel.
 11. The method of claim 9, wherein thedownlink control channel is modulated using the demodulation referencesignal.
 12. The method of claim 9, wherein the uplink control channelcarries the ACK/NACK information for a downlink shared channel scheduledby the downlink control channel.
 13. A base station in a wirelesscommunication system, the base station comprising: a processorconfigured to determine a specific uplink resource based on at least oneparameter for a downlink control channel. a radio frequency (RF) moduleconfigured to receive an uplink control channel using the specificuplink resource; and wherein the at least one parameter for the downlinkcontrol channel includes a value derived from an antenna port index of ademodulation reference signal associated with the downlink controlchannel.
 14. The base station of claim 13, wherein the at least oneparameter comprises one of downlink resource indexes associated with thedownlink control channel.
 15. The base station of claim 13, wherein thedownlink control channel is modulated using the demodulation referencesignal.
 16. The base station of claim 13, wherein the uplink controlchannel carries the ACK/NACK information for a downlink shared channelscheduled by the downlink control channel.